CCL: GAMESS Convergence Problem

Dear Brad,
 Thank you very much for your response.
 I actually used ICUT=11 and still there is a problem in the convergence.
 Here is the warning message:
 THE INPUT BASIS SET CONTAINS APPROXIMATE LINEAR DEPENDENCE.
  THE SMALLEST EIGENVALUE OF THE OVERLAP MATRIX IS   5.173593E-09
  THERE ARE   18 EIGENVALUES LESS THAN QMTTOL=  1.00E-06
  EIGENVECTORS BELOW -QMTTOL- ARE DROPPED FROM THE MO SPACE,
  IN ORDER TO ELIMINATE THE APPROXIMATE LINEAR DEPENDENCE.
  THIS WILL MOST LIKELY CHANGE THE ENERGY ON THE ORDER OF TENS OF
 MICROHARTREES,
  DEPENDING ON THE NUMBER OF ORBITALS REMOVED.  THE VALUE OF QMTTOL CAN BE
  CHANGED IN $CONTRL: JOBS WITH EIGENVALUES BELOW 1.0E-07 PROBABLY WON'T
  CONVERGE.  EIGENVALUES BETWEEN 1.0E-07 AND 1.0E-06 MAY REQUIRE LOOSENING OF
  THE DENSITY CRITERION (CONV IN $SCF), MORE ACCURATE INTEGRAL EVALUATION
  (ICUT=11 IN $CONTRL), MORE ACCURATE DIRECT SCF FOCK MATRIX
  CONSTRUCTION (FDIFF=.FALSE. IN $SCF), OR CHANGING THE SCF CONVERGER
  (DIIS=.TRUE. IN $SCF).
 I think that you meant QMTTOL, but how to loosen it without affecting the
 accuracy?
 I will also try what you suggested about the diffuse functions.
 Regards,
 Sara
 On Thu, Jul 6, 2017 at 3:31 PM, Brad Rose brose-x-live.com <
 owner-chemistry**ccl.net> wrote:
 >
 > Sent to CCL by: "Brad  Rose" [brose{}live.com]
 > Dear Sara,
 >
 > SCF convergence will be a problem with all the diffuse functions. It
 > takes time and practice to learn how to tell what could be the cause,
 > something worth your time if you plan on doing this work. The first thing
 > I would consider is the integral cutoff values, these are ICUT and one
 > other parameter that I don't recall offhand, I believe there should be a
 > warning in your output about the integral cutoffs if you are running into
 > linear dependancies (you likely are with all the diffuse functions
 > present). To get a reasonable geometry close to the local minima I would
 > suggest removing the diffuse functions from all but the anion and add
 > dispersion correction (the dispersion correction is computationally
 > cheap).
 >
 > Regards,
 > Brad Rose
 >
 >
 >
 > Sent to CCL by: "Sara  Mahmoud" [smahmoud%x%sci.cu.edu.eg]
 > Sent to CCL by Sara[smahmoud|*|sci.cu.edu.eg]
 > Dear all,
 >
 > I'm trying to study the adsorption of some ions on graphene flakes using
 > GAMESS-US program. When I optimize the ion-graphene system I get this
 > error message after several points of optimization.
 >
 > ***** FAILURE TO LOCATE STATIONARY POINT, SCF HAS NOT CONVERGED
 >      UPDATED HESSIAN, GEOMETRY, AND VECTORS WILL BE PUNCHED FOR RESTART
 >  **** THE GEOMETRY SEARCH IS NOT CONVERGED! ****
 >
 > I am using the DFT functional B3LYP with 6-31+G(d) basis set as a
 > starting level of calculation, I'm going to justify both the functional
 > and basis set and then include the suitable dispersion corrections in
 > single point energy calculations. This is some of the input I used:
 >
 > $CONTRL MAXIT=200 ISPHER=0
 > $SCF DIRSCF=.T. SOSCF=.F. DIIS=.T. SHIFT=.T. DAMP=.t.
 > $STATPT OPTTOL=0.00045 NSTEP=300
 >
 > I'm a new student in the field and have no experience in GAMESS-US
 > program. What I need to know is how can I get my jobs converged? and what
 > are the keywords that should I use to improve the SCF convergence for
 > this kind of interaction (ion-pi-system interaction)?
 >
 > Any help concerning this point will be highly appreciated.
 > Thanks in advance for all of you.
 > Sara>
 >
 >
 --
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